FIG. 1 shows a UV lamp system 10 which employs a cavity 13. The UV lamp system 10 includes a housing 15, a radio frequency (RF) or microwave wave energy source 11 (e.g., a magnetron) within the housing, and a waveguide 12 coupled to the energy source 11 within the housing 15. A space 13 remaining between the waveguide 12 and one end of the housing 15 forms a cavity 13. A UV bulb 14 is arranged in the cavity 13 of the housing 15.
The microwave energy generated by the magnetron 11 is supplied to the cavity 13 thorough the waveguide 12. Inside the cavity 13, the microwave energy is coupled to the UV bulb 14, and excites one or more elements contained in the UV lamp 14 (for example, Hg), causing the UV bulb 14 to emit ultraviolet (UV) light of a line wavelength (e.g., 365 nm). In FIG. 1, the UV bulb 14 has a 10 inch. Longer length bulb may be employed depending on the application to which the UV lamp system 10 is applied.
More recently, a new type of UV lamp that does not require a cavity has been developed. For example, U.S. Pat. No. 7,095,163 describes one example of the cavity-less UV lamp.
FIG. 2 shows a schematic view of the UV lamp 20 disclosed in U.S. Pat. No. 7,095,163. The UV lamp 20 includes a coaxial glass bulb 21 filled with Hg vapors and Ar gas. The UV lamp 20 further includes an antenna 22 inserted in a space formed by coaxial glass bulb 21 as a microwave coaxial probe. Microwave energy is supplied through the antenna 22 to excite the Hg vapor enclosed in the glass bulb 21.
In a UV lamp system comprising a plurality of electrodeless bulbs, a separate lamp may be required for each wavelength range for which UV exposure is required. In addition, because each bulb of the plurality of bulbs emits a sufficient amount of light to cure a substrate in a relatively narrow wavelength range. As a result, broadband exposure of a substrate cannot be achieved.